The donkey calf raise, also referred to as the bent-over calf raise, is an exercise that targets the calf muscles. These muscles are the gastrocnemius, consisting of the inner and outer calf muscle, and the soleus. Together, these calf muscles are known as the triceps surae, or three-headed calves. All three triceps surae muscles insert at the Achilles tendon, or calcaneus tendon. However, they each have a different origin.

Gastrocnemius

The main calf muscle worked during the donkey calf raise, due to the straight-leg position, is the gastrocnemius. The inner, or medial head, originates at the medial head of the femur, or thigh bone. The outer, or lateral head, originates at the lateral condyle of the femur. Both heads span down the back of the lower leg and converge into the calcaneus tendon. The gastrocnemius mainly functions as a plantarflexor, or extensor of the ankle. This is the primary movement you perform during the donkey calf raise. Since the gastrocnemius crosses the knee joint, where it originates at the femur, it also functions as a flexor of the knee, thus helping to bend knee.

Soleus

The soleus acts as an assisting mover to the two-headed gastrocnemius during the donkey calf raise. This muscle is flat-shaped and located deep below the gastrocnemius. The soleus is a single-joint muscle, as it originates at the back of the tibia, or shin bone, and crosses the ankle joint to inset in the calcaneus tendon alongside the gastrocnemius. To place more emphasis on the soleus while doing donkey calf raises, bend your knees. Doing so causes slack to the multi-jointed gastrocnemius, thus reducing its involvement. The more you bend your knees, the less gastrocnemius you work, and the more soleus you work.

Other Calf Raise Exercises

In addition to doing donkey calf raises, you should perform two other exercises, one that emphasize your gastrocnemius, and one for the soleus. The standing calf raise, done with your knees extended, is one of the best movements for building the mass and strength of your gastrocnemius. To best work your soleus, perform the seated calf raise. When doing this exercise, your knees are bent at a 90-degree angle, thus allowing you to effectively stimulate your soleus muscle.

Calf Training Tips

When training your calves, you must tailor your repetition schemes to accommodate the muscle fiber make-up of the muscles. Your gastrocnemius as a whole is made up of about a 50:50 ratio of slow to fast-twitch muscle fibers. The fast-twitch fibers are the ones that grow the most when you resistance train, so you should primarily use a lower rep count in the eight to 12 range using heavy weights to best build the muscle group. Do only a couple sets consisting of higher repetitions. In contrast, the soleus is made up of about a 90:10 ratio of slow to fast-twitch muscle fibers. So, you should primarily use higher repetitions when working this muscle, in the range of 25 to 50, and do only a few sets of lower repetitions sets.

References

About the Author

Richard Choueiri is a fitness and nutrition expert and the author of "The Human Statue Workout." He began writing professionally in 2007 and his work has been featured in Bodybuilding.com and "Physique Magazine." Choueiri studied exercise science and nutritional science at Rutgers University. He holds an American College of Sports Medicine CPT, and a National Exercise and Sports Trainers Association CMMACC.